1. Field of the Invention
This invention relates to a drawbar for coupling together railway cars in a fashion to provide unit train service while providing horizontal and vertical angling of the drawbar and eliminating slack in the coupling system of parts. More particularly, the present invention relates to such a drawbar wherein a vertical pivot pin engages walls of a carrier housing to provide an arrangement that minimizes friction between the parts during angling and allows for a quick disconnect between the drawbar and the railway car.
2. Description of the Prior Art
Conventional E-Type; F-Type and E/F-Type railroad couplers are relatively complicated assemblies used in conjunction with a car sill, draft gear, yoke, follower blocks, striker, pin or coupler connection. Such conventional coupler arrangements have a degree of free and cushioned slack. That is, there is a certain amount of free "play" between the coupler components when the load changes from a draft to a buff load and vice versa. At the same time, the draft gear acts as a spring mechanism to cushion impacts between adjacent cars. It has been found that eliminating the free and cushioned slack within a train will eliminate over the road train action forces due to "run-ins" and "run-outs". The magnitudes of these forces are large and cause significant wear and tear on the rolling stock. In some instances the forces are severe enough to cause derailments.
Furthermore, in conventional coupler assemblies, the key or pin connection of the coupler to the yoke is at a relatively long distance from the kingpin about which the wheel truck rotates. In negotiating curves, particularly under buff loading conditions, this gives rise to relatively large lateral forces which can cause derailment. The same is true when jackknifing occurs under buff loads with lateral forces attempting to rotate the cars about their centers.
In U.S. Pat. No. 4,580,686 there is disclosed a slackless self-adjusting rotary drawbar for railway cars which allows a railway car to be rotated in unit train service independent of the railway cars coupled thereto to effect a dumping operation of cargo as usually contained in a hopper of a railway car. This known drawbar arrangement requires that the drawbar have essentially hemispherical buff and draft load bearing surfaces on the forward and rear portions of a enlarged spherical butt end portion. Each of the hemispherical surfaces engage with corresponding front draft and rear buff bearing blocks that are in turn contained within a center sill by rear draft lugs and front draft lugs. The draft lugs are secured by weld metal to the center sill. Slackless operations are achieved by a gravity wedge operatively arranged between the rear draft lugs and the buff load bearing block. The components of the drawbar arrangement are contained within the center sill by a bottom plate attached to oppositely extending flange sections of the center sill. The spherical contour provided on the enlarged butt end portion of the drawbar is necessary to achieve rotary operation of one railway vehicle with respect to the adjoined vehicle connected thereto by the drawbar. While this drawbar has many desirable features including the rotary dumping feature when such features are not necessary it has been found that the large surface area formed by the hemispherical buff and draft surfaces impose unusually large frictional forces that may impede necessary freedom for angling of the drawbar relative to the center sill. Moreover, the multiplicity of dissociated parts particularly, for example, the front and rear draft lugs renders alignment of the hemispherical buff and draft bearing surfaces difficult to achieve and maintain. Non-alignment between such bearing surfaces may produce unwanted train action forces. The present invention is designed to provide a slackless drawbar arrangement where rotary dumping is not required to overcome the shortcomings and disadvantages of the drawbar arrangement disclosed in the aforesaid U.S. Pat. No. 4,580,686.